Program Project CORE (Jacquin, Rhoades) - Seven facilities/functions will be made available: 1) A single "morphometry" facility in St. Louis for staining and analyzing the long-range projections and dendrites of single trigeminal neurons, and for analyzing spatial distribution patterns of populations of trigeminal neurons, during normal development and after various experimental perturbations. Drs. Jacquin, Arends and Woolsey will oversee its use by all of the Program Project participants. 2) A single electron microscopy facility in St. Louis for tissue processing and documentation of ultrastructural reorganization during normal development and after experimental manipulations. Dr. Zahm will oversee its use. 3) A single tissue culture facility in Toledo for assessing the role of afferent-and target-related factors in axon target selection and the development of axon arborization patterns. Dr. Hankin will oversee its use. 4) A single facility in Toledo for the housing and preparation of experimental animals. Dr Rhoades will oversee its use. 5) Timely transmission of baseline data, experimental materials and ideas between the different laboratories. 6) External review by an External Advisory Committee and invited seminar speakers. 7) Administration. By instituting these CORE facilities and functions we: 1) Make technical upgrades developed in one laboratory available to all of the component projects. 2) Make optimum use of individual experimental animals to increase the power of conclusions drawn. 3) Ensure that the data obtained from the different laboratoaries are comparable and analysed in a like manner so as to circumvent common pitfalls associated with the correlation of findings obtained by independent observers and different analytic techniques. 4) Provide means for experimental and conceptual integration and facilitation. 5) Provide frequent and regularly scheduled meetings for internal and external reviews of our progress. 6) Administer the various projects. All requisite equipment and personnel are currently funcitoning within our Program Project.